大车前合子及原胚发育的超微结构研究

利用透射电镜技术研究了大车前（Plantago major L.）合子及其原胚发育特点。结果如下：大车前胚胎发育类型为柳叶菜类型。合子发育过程中，合点端的细胞壁逐渐形成，合子体积增大，极性增强，质体内贮藏淀粉。合子分裂通常发生在初生胚乳核分裂之后，第1次横分裂形成基细胞和顶细胞。基细胞经多次分裂形成单列细胞构成发达的胚柄；顶细胞多次分裂形成胚体，胚体细胞核大，核仁明显，细胞器的种类与数量多，呈现旺盛分生能力，具有很高的代谢活性。原胚发育过程中，小球胚初期，胚胎发育的营养物质主要来自合子储存的以及胚柄吸收并转运的营养物质；小球胚至中球胚期，胚柄组织迅速发育，依赖发达的胚柄自珠被组织吸收营养物质并转运至胚体；大球胚后期，胚柄开始解体，胚体外围细胞吸收胚乳的降解物作为胚胎发育所需营养物质。

Ultrastructural Studies on the Development of Zygote and Proembryo in Plantago major

An experiment was conducted by using TEM to study the ultrastructural changes in zygote and proembryo of Plantago major L. The results were as follows：Embryonic development of Plantago major L. was epilobium type. With the development of zygote，cell wall gradually formed，the volume increased，the polarity inhanced，and starch began to store in plastids. The zygote divided into basal cells and apical cells in first cross division after the primary endosperm nucleus division. Basal cell formed a single line cells after several times division，which developed into suspensor. Apical cell formed embryoid body after several times cell division. There were very large cell nucleus with obvious nucleolus and many variety types of organelles in embryoid body cells. These organelles of embryoid body cells had strong meristematic ability and high metabolic ability. In the early stage of small ball embryo，nutrients were from the storage of zygote，absorption and transport by suspensor. In the early stage to middle stage of small ball embryo，the suspensor tissue developed rapidly by absorping nutrients from integument andtransporting them to embryoid body. In the late period of big ball embryo，suspensor disintegrated and embryonic body peripheral cells absorbed the degradation products of endosperm cells as the nutrients for embryonic development.